I drive a BMW Z4 Roadster, and right now I'm looking to get some new amps/woofers in it.
And on topic, if I were you, I'd fix up the 72 Cadi...I mean, imagine how nice you could get that think. And with a nice engine, that could waste a Mustang in a race any day. I would work on the Cadi in a heartbeat. If it was a 60s model of the Stang, however, I would have to chose that.